Silica gel-alumina supported catalyst



Patented Nov. 8, 1949 I g UNITED STATES PATENT OFF smca GEL-ALUMINAsUrroa CATALYST Edwin T. Layng, New York, N. Y., assignor to The M. W.Kellogg Company, Jersey City, N. 1., a corporation of Delaware NoDrawing. Original application June 18, 1942,

2,487,564 ICE Serial No. 447,587.

Divided and this application April 19, 1946, Serial No. 663,823

l This invention relates to improvements in hydrocarbon conversionprocesses utilizing catalyst compositions comprising a minor proportionof a catalytically active material in combination with a majorproportion of an alumina carrier. More particularly, the inventionrelates .to improvements in hydrocarbon conversion processes utilizingcatalyst compositions comprising 'a major proportion of an aluminacarrier in combination with a minor proportion of an activating oxidesuch as an oxide of a metal of the lefthand columns of groups IV. V andVI of the periodic table. More particularly, the invention relates toimprovements in hydrocarbon conversion processes, such as hydrogenation,dehydrogenation, reforming and aromatization, by

means of a catalyst composition comprising a major proportion of acarrier material comprising alumina in combination with a minorproportion of an activating oxide, such as molybdenum oxide. Theinvention also relates to an improved catalyst comprising a minorproportion of a catalytically active material in'combination with amajor proportion of a carrier comprising alumina, and methods forpreparation thereof.

Catalyst compositions comprising minor proportions of catalyticallyactive materials, such as oxides of metals of the left-hand columns ofgroups IV, V and VI of the periodic table, in combination with a majorproportion of an alumina carrier material have been suggested for use inthe promotion of many hydrocarbon conversion reactions. Such catalystshave been employed extensively in the treatment of liquid hydrocarbonsin processes involving dehydrogenation and cyclization and otherreactions incidental to the reforming of naphtha. For example, catalystcompositions comprising a minor proportion of molybdenum oxide incombination with a major proportion of alumina have gone into extensiveuse in the reforming of naphtha of low anti-knock value under conditionseffective to dehydrogenate and cyclicize aliphatic hydro.- carbons. Suchcatalytic compositions also are used in the dehydrogenation of normallygaseous paraflin hydrocarbons to form corresponding olefins and in thedehydrogenation of olefins, such as the dehydrogenation of butene tobutadiene.

In the use of catalyst compositions of this character the hydrocarbonreactants are passed, in the'vapor form ordinarily, through a fixedbody, or mass, of granular catalytic material at the desired reactiontemperature, the endothermic heat of reaction being supplied to thereaction zone. The conditions necessary for the hydrocarbon conversionreactions result in side reactions which cause the formation anddeposition of high-boiling hydrocarbons which are readily converted bythe heat of the reaction to solid carbonaceous deposits on the surfacesof 8 Claims. (01. 252-455) the catalyst. Certain of the activatingoxides, such as molybdenum oxide, are gradually reduced during theoperating run from the state of oxidation representing maximum catalyticactivity to lower states of oxidation and even to the metalliccondition. This gradual reduction also has the effect of deactivatingthe catalyst.

The removal of carbonaceous deposits from the catalyst surfaces and therestoration of the activating oxide are accomplished ordinarily bypassing an oxygen-containing gas such as a mixture of air and flue gasover the temporarily deactivated catalyst mass to burn the carbonaceousdeposits from the catalyst surfaces and restore the activating oxide tothe desired state of oxidation. The amount of oxygen in the gas isrestricted ordinariiy'to a relatively low per-=- centage, for example 2to 4 per cent, so that the heat capacity of the regenerating gas issufflcient to prevent overheating of the catalyst mass by the combustionof the carbonaceous deposits.

Many of the activating oxides such as those of chromium and molybdenumare oxidized during the regeneration step to a relatively high state ofoxidation. The higher oxides thus produced are reduced relativelyrapidly during the initial period of the subsequent reaction step bycontact with the hydrocarbon reactants or with hydrogen which is formedin the reaction zone or introduced with the hydrocarbon reactants, to alower state of oxidation. It is this lower, and apparently more stable,state of oxidation in which the activating oxides probably exhibit thegreatest catalytic activity and from which they are slowly reduced to aneven lower state of oxidation or to the metallic condition during theoperating run.

Since the reduction reaction is exothermic the relatively rapidreduction of the activating oxide which occurs at the beginning of theoperating run may cause an undesirable temperature rise in the reactionzone. The reduction-reaction also consumes hydrogen which mightotherwise assist in retarding the deposition of carbonaceous material onthe catalyst surfaces. In order to avoid any undesirable fluctuation ofthe reaction temperature at the beginning of the run and in order toavoid any reduction in the desired concentration of hydrogen in thereaction zone it may be desirable to subject the regenerated catalystmass to a preliminary reduction treatment prior to the repassage of thehydrocarbon reactants through the reaction zone. This is accomplishedconveniently by contacting the catalyst mass with thehydrogen-containing gas which is ordinarily recycled to the reactionzone for admixture with the hydrocarbon reactants. Thereafter thepassage of the hydrocarbon reaction mixture through the reaction zonealong with the hydro- (i0 gen-containing gas is initiated.

In any' case, the oxidation and reduction of the activating ingredientof the catalyst'represent a substantial part of the oxygen and hydrogenrequirements of the process and res lt in the presence of water in thereactionzone which may have a deleterious effect on the catalyst andwhich must be separated from the reaction products. The oxygenrequirement of the process is important, not because of the materialcost of the oxygen but because of the bulk of the regenerating gas whichmust be passed through the reactor in the regeneration step. The bulk ofthe regenerating gas is many times the bulk of the oxygen containedtherein so that the oxygen requirement of the process involves thehandling, heating, compression, volume of regenerating gas. Thisrepresents a substantial part of the cost of the operation in terms ofenergy and apparatus costs. The hydrogen requirement of the operation,whichis due to the reduction of the catalyst, requires supplying to the"reaction zone a substantial quantity of hydrogen in addition to theamount which may be supplied thereto to maintain the proportion ofhydrogen in the reaction zone which is necessary to retard thedeposition of carbonaceous deposits on the catalyst surfaces.

The operating factors involved in the consumption or oxygen and hydrogenand the formation of water as a result of the successive oxidation andreduction of the activating ingredient of the catalyst ordinarilynecessitate the use of the catalyst under conditions involvingrelatively long operating runs between regenerative steps andsubstantially preclude the use of a catalyst containing a substantialproportion of such an activating ingredient in operations which requirethe employment of relatively short periods between regenerative stepssince each oxidation and reduction of the catalyst involves the samerequirement of hydrogen and oxygen and the same production of waterregardless of the quantity of carbon removed from the catalyst byoxidation.

It is an object of the invention to provide a hydrocarbon conversionprocess employing an improved catalyst of the character describedwherein the same activity level is attained with the use of a catalystcontaining a substantially smaller proportion of the activatingingredient which is subject to oxidation and reduction during theregeneration and' reaction steps of the process whereby the oxygen andhydrogen requirements of the process are substantially reduced, thusreducing the cost of the operation or permitting the employment ofoperations involving relatively short reaction periods and frequentregenerative steps. It is a further object of this invention to providea hydrocarbon conversion process employing an improved catalystcomposition which eflects improved results in the form of superiorproducts and higher yields. It is a further object of the invention toprovide an improved catalyst composition and a preferred method ofpreparation to obtain catalysts 'of maximum activity.

The alumina employed preferably is a syn thetic or natural materialwhich has been formed as a hydrate and which has been substantiallydehydrated at temperatures in the range of 600 and 1400" F. Preferablythe aluminum hydrate is heated to substantially complete dehydration at1200 F. One form of alumina which may be employed in the process isactivated alumina which is prepared by removing and dehydrating thescale which is deposited on the walls of the etc. of a substantialprecipitation tanks employed in 'the Bayer process. Another form ofalumina which may be employed in the preparation of the improvedcatalyst is obtained by dehydration of Synthetic aluminum hydrate.

Synthetic aluminum hydrate may be obtained by precipitation from asodium aluminate solution by the Bayer process. In this process bauxiteis treated with a strong solution of caustic soda in a closed vesselunder steam pressure. The resulting sodium aluminate solution isfiltered to separate the insoluble impurities and is then passed to theprecipitating tanks. A small amount of freshly precipitated aluminumhydrate is added to the solution, and the contents of the precipitatingtanks are then stirred for some time to effect a precipitation of a.large proportion of the alumina in the solution, which occurs as theresult of hydrolysis. By another method of preparation bauxite is fusedwith sodium carbonate to form sodium aluminate. The fused mass is thenleached with hot water, and the resulting sodium aluminate solution isfiltered. The aluminum hydrate is precipitated from the sodium aluminatesolution by the passage of carbon dioxide therethrough.

While specific reference is made in the following description to' theuse of activated alumina or aluminum hydrate in the preparation of theimproved catalyst, it is to be understood that the invention is notlimited thereby and that the advantages of the invention are obtained inthe use of any suitable alumina of the general character describedabove, such as alumina gel, which may be prepared, for example bypeptizing aluminum hydrate or by precipitation from aluminum sulfatesolutions with ammonia.

In the following description of the invention the minor proportion ofthe more active ingredient employed in combination with a majorproportion of the alumina is referred to as the activating oxide. Asactivating oxides which may be combined with alumina to form a catalystof high activity in the promotion of hydrocarbon reactions reference ismade to the oxides of metals of the left-hand columns of groups IV, Vand VI of the periodic table, including chromium, molybdenum, tungsten,uranium, vanadium, columbiuni, tantalum, titanium, zirconium, cerium,hafnium and thorium. In the specific examples set forth below molybdenumoxide is employed as the activating oxide in combination with thealumina supporting material. It is to be understood, however, that theimprovements represented by this invention are applicable to catalystscomprising a major proportion of alumina and other activating oxides andthe hydrocarbon conversion processes employing such other catalystcompositions.

In accordance with the present invention the catalyst compositioncomprising a major proportion of alumina in combination with a minorproportion of an activating oxide is modified by the incorporationtherein of silica in a proportion suflicient to enhance the catalyticactivity of the catalyst composition but insufllcient to diminish theactivity of the catalyst in promoting the desired reactions which areproduced by the catalyst composition in the absence of silica. Forexample, in the modification of the catalyst composition for use inpromoting the reforming of naphthas to gasoline constituents of highantiknock value the silica is incorporated in the catalyst compositionin a proportion suflicient to enhance the catalytic activity of thecatalyst comi 6 stantially reducing the activity of the catalystcomposition inthe promotion of reactions such are the beneficial effectof the addition of silica.

In accordance with the preferred method of preparation silica iscombined with the other ,ingredients of the catalyst composition in theform of silica gel when the alumina is employed in the form of aluminumhydrate or activated alumina. However, the invention is not limited tothe use of catalysts prepared from silica gel. For example, other formsof silica may be employed if the alumina is present in the form ofalumina gel or if theconditions of mixing the ingredients are regulatedto effect substantial peptization of the silica. I

In the preparation of catalyst compositions comprising a smallproportion of an activating oxide and a major proportion of alumina theingredients may be combined by forming the alumina into a paste or moistmass with a solution containing a suflicient quantity of a molybdenumcompound to form the desired proportion of the molybdenum oxide in thefinished catalyst, or the alumina may be immersed in a solution of themolybdenum compound under conditions effective to cause the absorptionof a sumcient amount of the molybdenum compound solution to deposit inand on the alumina particles the desired quantity of the molybdenumcompound. The first-mentioned method, involving the formation of a pasteor moist mass, is preferred in connection with this invention because ofthe relative ease of incorporating the silica. However, the invention isnot limited to the use of catalysts prepared in that manner since theimproved catalyst may be preferred by the method involving immersion orany other suitable'method of combining the desired ingredients of thecomposition.

While the activating oxide, such as molybdenum oxide, may beincorporated in the mixture as such, it is preferred, in order to obtaincatalysts of maximum activity, to incorporate the activating oxide inthe form of a solution of a soluble compound of themetal, the solublecompound being one which upon heating to a temperature insuflicientlyhigh to injure the catalyst structure, decomposes to produce the desiredoxide. For example, molybdenum oxide may be incorporated in the catalystcomposition in the form of ammonium molybdate.

The quantity of molybdenum oxide required in the improved catalystcomposition varies ordinarily from 1 to 12 weight per cent, althoughsmaller or larger proportions may be employed. Maximum activity isobtained in catalysts containing molybdenum oxide in the range Of 6 to 9weight per cent. Proportions higher than 9 weight per cent apparently donot increase the activity of the catalyst composition to a degree whichjustifies the expense of preparation and the use of catalysts employingsuch high proportions of this relatively expensive material.

. The proportion of silica necessarily is limited to the amount whichenhances the catalytic activity of the catalyst composition withoutsubas dehydrogenation and aromatization. Preferably, the ratio ofaluminato silica should be greater than iii, and ratios less than 3;?ordinarily may not be employed without substantially alteringthejcharacter of the catalyst composition and reducing its activity inthe promotion of reactions for whichthe catalyst composition has arelatively high activity in the absence of silica. The beneficial effectof silica in the catalyst composition is obtained by the incorporationof amounts as small as 1 per cent or less of the silic'ain the catalystdecomposition. Ordinarily,

however, larger amounts are preferred. In general, the silica andalumina should be employed in the improved catalyst composition in aweight ratio of alumina to silica in the range of 3:7 to 99:1. Withinthis range, however, it is found that relatively high propo ions ofsilica impart to the catalyst composition a greater activity intheformation of carbon. In the preparation of catalysts for use inoperations in which carbon formation is a serious factor it isdesirable, therefore, to employ only the proportion of silica which isnecessary to enhance the activity of the catalyst composition to thedesired degree. For this reason it is undesirable ordinarily to employ aproportion of silica higher than that which produces catalystcompositions of maximum activity. Consequently, a weight ratio ofalumina to silica in the range of 7:3 to 97:3 is satisfactory in thepreparation of catalysts for most uses. In catalyst compositionscomprising a small proportion of the activating oxide in combinationwith a carrier essentially consisting of alumina and silica it is foundthat the optimum weight ratio of alumina to silica is in the range of4:1 to 19:1.

When employing alumina. in the form of activated alumina or calcinedaluminum hydrate in the preparation of the improved catalysts it ispreferred to combine thesilica therewith in the form of silica gel.Preferably, the silica gel should be mixed with the ingredients while ina state of substantial hydration. In order to obtain the advantages ofthe improved process to the fullest degree, the silica gel should bemixed with the other ingredients of the catalyst composition whilecontaining at least 10 weight per cent of water. Preferably,the-,v'v'ater of hydration of the silica gel should-be at least 50 percent, for example to per cent by weight.

The catalyst is prepared conveniently by a modification of the generalmethod described above involving the formation of-a paste. By I thissimple method silica gel in a state of substantial hydration, asdescribed above, is intimately mixed with the other ingredients to forma paste or moist mass after which the method of preparation follows thegeneral procedure described above. The catalyst also may be formed byfirst mixing silica gel with the alumina and forming the mixtureintopellets which are then immersed in a suitable solutioniof a molybdenumcompound. In the method of preparation involving the formation of amoist mass or paste, which is preferred because of its simplicity, thesilica gel preferably is first mixed with the alumina, after which thepaste is formed by combining the intimately mixed silica gel and aluminawith the molybdenum compound solution.

The invention will be described further by reference to the preparationof specific catalysts which illustrate the various methods ofpreparation of the other catalysts.

tion described above and by reference to the testing of such catalystsunder uniform conditions to indicate the effect of such variations inthe method of preparation on the activity of the catalysts.

In the preparation of these catalysts activated alumina suflicientlyfinely powdered to pass an 80 mesh screen and silica gel in variousdegrees of hydration and also sufficiently finely powdered to pass an 80mesh screen were employed. The alumina and silica gel were mixed with asolution containing ammonium molybdate, the proportions of theingredients being regulated to produce in the finished catalyst 6 weightper cent of M: and weight per cent of $102, the remainder beingalumina.In the single preparation containing no silica the alumina was made intoa paste directly with the ammonium molybdate. In all other preparationsexcept the last two the alumina was first mixed with the silica gel, andthe resulting mixture was then combined with the requisite amount ofammonium molybdate solution to form a paste or wet mass. In the last twopreparations, which will be discussed specially, a different order ofsteps in combining the ingredients was employed. In all preparations thefinal moist mixture or paste was heated at 1200 F. for one hour andthen, after cooling, was formed into 1% inch pellets, 2 percent ofgraphite being added to facilitate pelleting.

The graphite, however, had no effect on the catalytic activity and isignored in the further consideration of the catalyst composition.

The variations in the preparation of the catalysts are given in Table Ibelow in which there is indicated the catalyst number, the quantity ofalumina employed and the water content thereof, the quantity of silicagel employed and the water content thereof, the quantity of ammoniummolybdate employed, and the volume of the solution containing theammonium molybdate.

TABLE I Ammonium Alumina Silica Gel Molybdam Catalyst Number WeightWeight Grams Percent Grams Percent Grams 0.0. 50!.

In the preparation of catalyst No. 467, referred to in Table I, thesilica gel was first creamed or slurried with 200 c. c. of water. Theammonium molybdate solution was then added to this cream, and theseingredients were thoroughly mixed. The mixture thus obtained was thenintimately mixed with the alumina powder. The resulting moist mass wasthen further treated in the same manner as in the preparation of theother catalysts.

In the preparation of catalyst No. 469, referred to in Table I, thealumina powder was first mixed with the ammonium molybdate solution. Thesilica gel was creamed with 150 c. c. of water, and the material thusobtained was then mixed with the mixture of alumina and ammoniummolybdate. The resulting moist masswas furthertreated in the same manneras in. the prepara- The catalysts whose preparations are outlined inTable I were all tested under identical conditions in the treatment of astraight-runEast Texas heavy naphtha having initial and and boilingpoints of 240 F. and 396 F., res ectively. The naphtha contained 14volume per ent aromatic hydrocarbons, 33 volume per cent naphthenes andno olefin hydrocarbons and had an octane number of 42.3, A. S. T. M. Thenaphtha was passed in the vapor form over the granular catalyst in asuitable reactor at a space velocity of 1 volume (liquid basis) per hourper volume of catalyst space. The reaction zone was surrounded by a leadbath which was maintained at a temperature of 950 F. The reactor wasmaintained under a gauge pressure of 200 pounds per square inch.Hydrogen was passed into the reactor with the naphtha charge at a rateof ap proximately 2400 cubic feet per barrel of naphtha.

Since it is known that molybdenum oxide catalysts sometimes do notdisplay full activity in the initial test run and prior to the firstregenera tion of the catalyst, all test data given in this specificationare limited to that obtained in the second operating runs on thecatalysts, following an initial operating run and a regenerationtreatment of each catalyst. In each regeneration treatment aregenerating gas consisting principally of nitrogen and other inertgases and containing 2 to 3 per cent of oxygen was passed through thereaction zone at the reaction temperature to ignite and burncarbonaceous deposits on the surfaces of the catalyst. This treatmentwas continued in each case until the temperatures in the reaction zoneindicated that no further combustion was occurring. The regenerationtreatment usually required about seven hours. Prior to the start of theoperating run following the regeneration treatment a hydrogen-containinggas such as a product gas from a previous operation was passed throughthe reaction zone at the operating pressure and temperature for a periodof about one hour. This treatment served to effect a preliminaryreduction of the molybdenum oxide to a relatively more stable condition.

Comparative results from the testing of the various catalysts listed inTable I in the manner described above are set forth below in Table II.

TABLE II Composition Wt. Per w t. Per Catalyst Cent Cent mo g-g Numberin Silica g g M00: SiOg A:

The data in Table II are arranged to show the effect, on the activity ofthe catalyst, of the condition of the silica during the preparation ofthe catalyst and the effect of the order of steps employed in combiningthe various ingredients of the catalyst composition. Catalyst No. 422was prepared with silica gel containing only a small amount of waterwith the result that the substitution of 5 per cent of silica for a likeamount of alumina produced an increase in octane number of 1 number. Onthe other hand, catalyst No. 432 was prepared with silica gel containinga fairly substantial amount of water with the result that an increase inoctane number of 4.

numbers was obtained. The use of silica gel contalning increasingamounts of water in the preparation of catalysts Nos. 500, 472 and 478produced further increases in the octane number of the naphtha to amaximum of 11 numbers above the octane number obtained with catalyst No.270, which contained no silica. It is evident, therefore, that incombining silica directly with the alumina for the preparation of theimproved catalyst the silica should be in the form of silica gelcontaining a substantial amount of water of hydration, for example,weight per 'cent or more. Preferably, the amount of water in the silicagel should be 50 weight per cent or more, with best results beingobtained with silica gel containing 85 to 95 weight per cent of water.

The data for catalysts Nos. 467 and 469 indicate that a certain order ofsteps in the mixing of the ingredients in this particular method ofpreparation of the improved catalyst is desirable to obtain the bestresults. In the preparation of catalyst No. 478 and the other catalystscontaining silica listed above catalyst No. 478, the silica gel andalumina were first intimately mixed, after which the solution containingmolybdenum compound was added to the mixture. This appears to be thebest procedure to follow in this particular method of preparation of thecatalyst. Catalyst No. 467 was prepared in a difierent order of steps inwhich the silica gel was combined first with the solution of ammoniummolybdate, the alumina then being added to the mixture. Inferior resultswere obtained with this catalyst. Catalyst No. 469 was prepared with astill different order 'of steps in which the activated alumina was firstcombined with the ammonium molybdate solution, the silica gel then beingadded to the combination. The results obtained with this catalyst alsowere inferior, indicating that the order of steps employed in thepreparation of catalyst No. 478 is to be desired' All further catalystpreparations described in this specification were made with the order ofsteps employed in the preparation of catalyst No. 478 in order toeliminate any variables which might otherwise result from a variation inthe order of preparative steps.

The .data in Table II indicate that when the alumina, in a form similarto that of activated alumina or calcined aluminum hydrate, is combineddirectly with the silica, the latter should be in the form of silica gelcontaining a substantial amount of water.' Furthermore, a certain orderof steps appears to be necessary in connection with this particularmethod of preparation in order to achieve the best results. It

is to be understood, however, that the invention is not limited to theuse of a catalyst containing alumina, silica and an activating oxideprepared by this method, but includes within its scope the use of anycatalyst, comprising alumina and silica in a desired ratio incombination with an activating oxide, prepared by any method whichimparts to the catalyst composition the improved characteristics whichare the beneficial effect of the addition of silica to the composition.

To illustrate the eflect of the addition of various amounts of silica tocatalyst compositions comprising various amounts of molybdenum oxide,and to exemplify the addition of titania or iron oxide to the catalystcomposition, reference is made to a number of catalyst preparationswhich were tested in the dehydrogenation and reforming treatment of thestraight-run scribed above.

In the preparation of these catalysts alumina, prepared by heatingaluminum hydrate at 1200' F. for three hours, was first mixed withsilica gel containing 86 to ,88 weight per cent water, and

the resulting mixture was then formed into a paste or moist mass bymeans of a solution containing ammonium molybdate in an amountsuificient to produce in the finished catalyst composition 2, 6 or 9weight per cent of M00: as desired. In the preparation of the catalystscontaining no silica the alumina was made into a paste directly with theammonium molybdate solution. Th final moist mixture or paste was heatedat 1200 F. for one hour. and then, after cooling, formed into 1"; inchpellets, 2 per cent-of graphite being added to facilitate pelleting. The

, graphite. however, had no effect on the catalytic activity and isignored in the further considera-.

tion of the catalyst compositions.

The silica gel employed was prepared by a method of which the followingis an example. 15 gallons of sodium silicate, containing 28.5 per centof S102 and 8.85 per cent of NaaO, were mixed with 15 gallons ofdistilled water. 3.2 gallons of technical grade 66 Baum sulfuric acidwere dissolved in 16.3 gallons of distilled water.

The acid solution was allowed to cool to room temperature. The sodiumsilicate solution was then added to the acid solution with vogorousstirring. The mixture was allowed to stand for 24 hours. The gel formedwas subdivided by passage through a inch screen and mixed with 35 gal,-lons of distilled water. This mixture was allowed to stand for at leastone hour, and the water was then removed. The gel was given 15 similarwashes of 35 gallons each. The last wash water was not removed from thegel but was stored with it. The pH value of the wash water increasedsubstantially from a value of 0.61 for the first wash water to 3.90 forthe 15th wash water.

The variations in the preparation of the catalysts are given in TableIII below in which there is indicated the catalyst number, the quantityof alumina employed and the water content thereof, the quantity ofsilica gel employed and the water content thereof, the quantity ofammonium molybdate employed, and the volume of the solution containingthe ammonium molybdate.

TABLE III Ammonium Alumina Silica Gel Molybdate Catalyst Number Wt P WtP erer- 0. c. Grams cent H10 Grams cent H10 Grams Sol.

' l. 4 0 0 14. 7 460 2. l 48. 4 87. 6 14. 7 475 l. 3 224 86. 6 14. 7 4854. 8 349 87. l 14. 7 490 0. 7 484 87. 6 l4. 7 325 4. 8 558 87. 1 14. 7465 0. 7 968 87. 6 14. 7 280 2. 1 0 0 44. l 450 0. 6 51. 7 88. 4 44. 1480 0. 6 103. 4 88. 4 44. l 480 0.6 259 88. 4 44. 1 465 1. 3 449 86. 644. l 445 4. 8 474 87. 1 44. 1 420 l. 3 895 86. 6 44. 1 395 0. 7 242087. 6 44. 1 7M 0. 7 4310 87.6 44. I 350 1. 1 0 0 66. 2 400 0. 7 48. 487. 6 66. 2 420 0. 7 96. 8 87. 6 66:2 420 0. 4 259 88. 4 66. 2 445 0. 7484 87. 6 66. 2 325 0. 7 968 87. 6 66. 2 $0 The catalysts whosepreparations are outlined TABLE IV Catalyst Composition, Wt. Percent B TM gm! t omm m u M; sio, T10, mo. Aho, Number In Table IV the data arearranged to show the eflect on the activity of the catalyst, asreflected by the ioctane number of the gasoline product, of theincorporation of various amounts of silica in the catalyst composition.In Table IV the data are also arranged to place the catalysts having thesame content of molybdenum oxide in groups to show the efiect of varyingthe silica content. Since the molybdenum oxide content of each group ofcatalysts is uniform the incorporation of the silica is in effect asubstitution of silica for a portion of the alumina.

The data for catalysts Nos. 518 and 502 show that the incorporation, orsubstitution, of 1' per cent silica in the catalyst compositionordinarily comprising 98 per cent alumina and 2 per cent molybdenumoxide produces a substantial increase in the octane number of thegasoline product. The incorporation of increasing amounts of silica inthe catalyst composition, in catalysts Nos. 491, 530 and 504, effectsfurther increases in the activity of the catalyst composition, as shownby the consistent increases in the octane numbers of the gasolineproducts to a maximum increase of 11 numbers which is achieved by theincorportion of per cent silica in catalyst No. 504. Further increasesin the amount of silica as illustrated by catalysts Nos. 531 and 505resulted in slight decreases in activity, indicating that for thisparticular catalyst composition the optimum percentage of silica isabout 10 per cent, although all of the various additions of silica from1 to 20 per cent produced catalysts more active than catalyst No. 518which contained no silica.

Referring in Table IV to the group of catalysts containing 6 per centmolybdenum oxide, it is seen that the incorporation of small amounts ofsilica in the catalyst wmposition produced substantial increases inactivity and that a maximum activity, as indicated by the octane numberof the gasoline product, was obtained with the incorporation of about 10per cent of silica in the catalyst composition. In this group ofcatalysts the increases in activity by the additions Of silica areindicated by smaller numerical increases in the octane numbers of thegasoline products. This is to be expected, however, since catalyst No.501, containing 6 per cent molybdenum oxide, was substantially moreactive than catalyst No. 518, containing 2 per cent molybdenum oxide. Inthe group of catalysts having 6 per cent molybdenum oxide it is to benoted that, while the maximum octane number was obtained with catalystNo.

,488 containing 10 per cent silica, improved activity isexhibited bycatalysts in this group having a wide range of proportions of silica.For example, catalyst No. 486 containing-2 per cent silica and 92 percent alumina and catalyst No. 489 containing 20 per cent silica and 74per cent alumina produced gasoline of the same octane number, which wasthree numbers higher than that of the gasoline produced by catalyst No.501 which contained no silica. In this group of catalysts the only oneexhibiting a lower activity as a result of the substitution of thesilica for alumina is No. 511 which contained 89 per cent silica and 5per cent alumina, which is, of course, far outside the range ofcompositions employed in the catalysts of the invention. It is evidentthat the incorporation of so large a proportion of silica in catalystNo. 511 with a corresponding drastic reduction in the proportion ofalumina in the catalyst, has produced a composition having propertiesdiflerent from those of the alumina-molybdenum oxide catalyst containingno silica, such as catalyst No. 501. Evidently the dehydrogenatingactivity of the alumina-molybdenum oxide composition has beensubstantially reduced by the incorporation of so large a proportion ofsilica. The activity of catalyst No. 511 is at about the same level asalumina alone and but little higher than that of a composition similarto that of catalyst No. 511 minus the molybdenum oxide.

As a part of the data relating to catalysts hav ing 6 per-centmolybdenum oxide there are included in Table IV operating results fromthe testing of catalyst No. 583 containing, in addition to alumina,molybdenum oxide and silica, a substantial proportion of titania. Thiscatalyst was prepared as follows:

Catalyst No. 583.-l00 pounds of titania acid cake were stirred with 20gallons of softened water. The resulting slurry was filtered in a pressand was washed in the press with 200 gallons of water. The resultingmoist cake contained 58.2 per cent water. 143.5 grams of the materialthus obtained were intimately mixed with 398 grams of alumina,containing 3.8 per cent water, obtained by heating aluminum hydrate forthree hours at 1200 F., and 890 grams of silica gel containing 87.1 percent water. The resulting mixture was made into a paste with 425 c. c.of a solution containing 44.1 grams of ammonium molybdate. The paste washeated at 1200 F. for one hour. After cooling the catalyst compositionwas made into inch pellets containing 2 per cent graphite. Thecomposition of this catalyst by weight was AlzOa-64 per cent, MoOa-6 percent, 8102-20 per cent, and TiOz-IO per cent.

Catalyst No. 583 was tested in the same manner as the other catalystswhose preparation is described in Table III, and the results, as setforth in Table IV. indicate that the addition of titania to the catalystalready containing silica produced a further increase in activity, as reflected by an increase in octane number. This apparently is not a merecumulative effect since emes t the addition oi a further and equivalentamount Referring in Table IV to the series of catalysts containing 9 percent molybdenum oxide, it is seen that the addition of silica to thecatalyst, as a partial replacement of alumina, produced an increase inthe activity of the catalyst, as reflected 'by an increase in the octanenumber oi. the gasoline product obtained. This beneficial result wasobtained even though the activity of catalyst No. 695, consisting of 91per cent alumina.

and'9-per cent molybdenum oxide, represents substantially the optimumcombination of these ingredients in an alumina-molybdenum oxide catalystcontaining no silica. As in the case of the catalysts containing 6 percent and 2 per cent of molybdenum oxide, the incorporation of increasingamounts of 'silica in the catalysts containing 9 per cent molybdenumoxide produces further increases in the activity of the catalysts, asreflected by the octane numbers or the products, to a maximum activitywhich was obtained by the incorporation of about 10 per cent silica. Theoctane number of the gasoline obtained with catalyst No. 508, containing10 per cent silica, was almost three numbers higher than obtained withcatalyst No. 695, containing no silica. While this increase isnumerically smaller than the increases obtained by the incorporation ofthe same proportion of silica in catalysts containing 2 and 6 per centmolybdenum oxide, the increase represented by catalyst No. 508 issubstantially as impressive, if not more so, in view of the initial highlevel of activity exhibited by catalyst No. 695. The incorporation ofamounts of silica substantially larger. than 10 per cent, as representedby catalyst No. 508, apparently produces smaller increases thantheaddition of 10 per cent of silica to the catalyst. I However, it shouldbe noted that, while amounts of silica substantially greater than 10 percent in the catalyst containing 9 per cent molybdenum oxide apparentlyare excessive if maximum octane number is desired, the activity of suchcatalysts containing amounts of silica substantially-larger than 10 percent, as represented by catalyst No. 509, is still substantially abovethat of the catalysts containing no silica, as represented by catalystNo. 695.

As an illustration of the efiect of the addition of iron oxide to thealumina-silica-molybdenum oxide catalyst test data for catalyst No. 538are included in Table IV. This catalyst was prepared as follows:

Catalyst No. 538.460 grams of alumina prepared by heating aluminahydrate at 1200 F. for

13 hours and containing 0.9 per cent water were mixed with 30 grams ofiron oxide (F6203) and 465 grams of silica gel containing 87.1 weightper cent water. These ingredients were intimately mixed, and to theresulting mixture were added 325 c. c. of a solution containing 66.2grams of ammonium molybdate. The resulting moist mass was heatedjat 1200F. for one hour and after cooling was made into inch pellets containing2 per cent graphite. This catalyst had the following composition inweight per cent: Al20a-.-76 per cent, SiO210 per cent, MOa9 per cent,and Fez03-5 per cent.

Catalyst 'No. 538-was tested in the same manner as the other catalystslisted in Table IV, and the 14 test data indicate a substantial furtherincrease in activity 01' the catalyst, apparently due to theincorporation of the iron oxlle. Comparing catalyst No. 538 withcatalyst No. 508, the latter representing apparently the optimumcombination of alumina, silica and molybdenum oxide, it is found thatthe substitution oi 5 weight per cent iron oxide for an equivalentquantity oi the alumina, as in catalyst No. 538, apparently produced asubstantial increase in activity, as represented by an increase inoctane number oi the product 01' over two numbers to 85.9. By coinparingcatalyst No. 538 with catalyst No. 695 it is seen that the substitutionof 10- weight per cent silica and 5 weight per cent iron oxide for anequivalent quantity of the alumina in catalyst No. 695 produced animpressive increase in activity, as represented by an increase of sixnumbers in the octane number of the gasoline product obtained. Thisresult is not cumulative since the incorporation of this amount of ironoxide in an alumina-molybdenum oxide catalyst containing no silicaordinarily lowers the activity of the catalyst.

The superior activity exhibited by the improved catalysts listed inTable IV apparently results, in part at least, from improvements in theactivity oithe catalyst in the promotion 01' dehydrogenation,cyclization and aromatization reactions, as evidenced by the increase inthe concentration of aromatic hydrocarbons in the gasoline products ofthe more active catalysts. For example, the debutanized gasoline productof catalyst No. 518 contained 35.2 volume per cent aromatichydrocarbons, whereas the corresponding ilgures for catalysts Nos, 491and 504 were 41.6 and 48.6. The debutanized gasoline product ofcatalystNo. 501 contained 52.4 volume per cent of aromatic.hydrocarbons, whereas the aromatic content of uct of catalyst No. 695contained 54.1 volume per cent of aromatic hydrocarbons, whereas thecorresponding figure for catalyst No. 506 was 58.2 volume per cent.

The improved catalyst has two important applications in hydrocarbonconversion processes ordinarily employing catalysts comprising aluminaand activating oxides such as molybdenum oxide. One application of theimproved catalyst to such hydrocarbon conversion processes is theemployment of a catalyst comprising alumina, molybdenum oxide and silicain the proportions which impart to the catalyst the maximum ac= tivityfor the reactions involved in the hydrocarbon conversion process. Thisordinarily involves the use of a proportion of molybdenum oxidecorresponding to the proportion which imparts maximum activity to analumina-molybdenum oxide catalyst containing no silica.-

A second application of the improved catalyst involves a hydrocarbonconversion operation employing a catalyst comprising alumina and aproportion of an activating oxide which, in the absence of silica, wouldimpart to the catalyst composition a substantially lower activity thanthat which would result from the employment of a greater proportion ofthe activating oxide. In this application of the invention, however, theactivity of the catalyst comprising a relatively low proportion of theactivating oxide, such as molybdenum oxide, is maintained at arelatively high level by reason of the presence in the catalystcomposition of a substantial proportion oi silica.

' proportion of the activating In the last-mentioned application of theinvention the hydrocarbon conversion processis promoted by a catalystcontaining a relatively low oxide,,the activity of the catalyst beingmaintained at a relatively high level by reason of the presence thereinof a substantial proportion of silica. This application of the inventionhas many advantages arising out of the use of relatively low proportionsof the activating oxides. Since the activating oxides ordinarily costsubstantially more per unit of weight than any other ingredient of thecatalyst composition this application of the invention permits asubstantial saving in the cost of the catalyst. This application of theinvention also has the advantage that it minimizes the oxygen andhydrogen requirements of the process which are attributable to theoxidation and reduction of the catalyst and also minimizes the formationof water in the reactor.

The use of catalysts comprising small proportions'of the oxidizable andreducible activating oxides which is made possible by the incorporationof silica therein in accordance with this invention substantiallyeliminates the objection to the use of catalysts comprising suchactivating oxides in hydrocarbon conversion operations involving shortoperating cycles and frequent regenerative steps since such objectionshave been based on the relatively large requirement in oxygen andhydrogen which would accompany conversion operations involving frequentregenerations of alumina catalysts containing the proportions ofactivating oxides which are necessary to impart satisfactory activity tothe catalyst in the absence of silica.

The two applications of the improved process are illustrated in Table Vbelow in which there are arranged for easy comparison operating dataalready presented in Table IV, as well as additional data. In Table Vthe data are arranged to show the effect of changes in catalystcomposition on the octane number, gasoline yield and carbon formationresulting from the use of the various catalysts in the treatment of theEast Texas heavy naphtha in the manner previously described.

TABLE V Catawstt gomoposition, 1 wt Catalyst er en Octane P o er CentPer Cent Number Number Gasoline Carbon M: Si 0: A 11 0 3 2 0 98 66. 592. 4 0. 4 1 84 66. 4 94. l 0. 6 6 0 94 76. 8 87. 3 0. 6 2 10 88 77- 690. 6 0. 8 6 1 93 77. 8 88. 8 0. 5 8 0 92 79. 2 86. 0 0. 8 9 0 91 79. 985. 7 0. 8 6 2 92 79. 6 B7. 5 O. 7 6 5 89 B1. 2 87. 2 0. 7 9 5 86 82. 687. 4 1. 0

The preparation of all the catalysts listed in Table IV has beendescribed above with the ex- The resulting paste was heated at 1200 F.forv one hour. After cooling, the catalyst was made into 1; inch pelletscontaining 2 per cent graphite. The finished catalyst had the followingcomposition in weight per cent: Al2O:i 84 per cent, SiO2-15 per cent,and MoOal per cent.

Catalyst No. D 523.560 grams of alumina prepared by heating aluminumhydrate for three hours at 1200 F. and containing 1.4 weight per centwater were mixed with 430 c. c. of a solution containing 58.8 grams ofammonium molybdate. The moist mass was heated at 1200 F. for one hourand then was made into inch pellets with a 2 per cent graphite. Thiscatalyst consisted of 92 weight per cent A120: and 8 weight per centMoOa.

' Referring in Table V to the data for catalysts Nos. 518 and 622, itwill be noted that catalyst No. 622, which contained one-half the amountof molybdenum oxide in catalyst No. 518, was subsilica permitted asubstantial stantially as active, apparently by reason of the presenceof 15 per cent silica and is otherwise satisfactory.

Referring in Table V to the data for catalysts Nos. 501, 504 and 485, itwill be noted that catalyst No. 504, containing one-third the quantityof molybdenum oxide contained in catalyst No. 501, gave equivalentresults, the slightly greater carbon formation being compensated for byhigher octane number. The data for catalyst No. 485 demonstrates that bymaintaining the percentage of molybdenum oxide the same as in catalystNo. 501 and incorporating a relatively minor proportion of silica theresults are improved as to octane number and carbon formation.

Referring in Table V to the last group of catalysts, catalysts Nos. 523and 695 represent alumina-molybdenum oxide catalysts of optimum activitysince catalysts having higher percentages of the molybdenum oxideordinarily do not exhibit higher activity. By the incorporation of -aminor percentage of silica, as in catalyst No.

486, the molybdenum oxide content may be substantially reduced withoutimpairing the activity of the catalyst. Catalyst No. 486 containing 25to 33 per cent less molybdenum oxide than catalysts Nos. 523 and 695produced results in the reforming of the naphtha at least as good as didthe catalysts containing the larger amounts of molybdenum oxide. Incatalyst No. 486 the incorporation of the small percentage of reductionof molybdenum oxide content without impairing the activity of thecatalyst. Catalyst No. 486 thus represents a reduction in the cost ofthe catalyst because of the smaller percentage of the relativelyexpensive molybdenum oxide employed, and permits more economicaloperation.

In Table V the data for catalyst No. 484 represent an operationinvolving both applications of the invention, since catalyst No. 484contains the same reduced quantity-of molybdenum oxide as catalyst No.486, wherefore the advantages of catalyst No. 486 in that connection arepresent also in catalyst No. 484. Catalyst No. 484 also contains silicain somewhat larger proportion than catalyst No. 486, as a consequence ofwhich the activity of catalyst No. 484 is substantially greater thanthat of catalyst No. 486 or catalysts Nos. 523 and 695, as representedby a higher octaine number in the gasoline product of the operation. InTable V the data for catalyst No. 506 represent the application of theinvention in which the proportion of molybdenum oxide in the catalyst ismaintained at about the optimum figure and the activity of the catalystis further enhanced by the incorporation of a. substantial proportion ofsilica. Comparing the data for catalysts Nos. 695 and 506, it is seenthat the incorporation of per cent of silica in the latter catalystproduced an increase in the octane-number of the gasoline product whichis substantial alumina suiliciently finely divided to pass an 80- meshscreen were made into a stiff paste with 280 c. c. of a solutioncontaining 44.2 grams of ammonium molybdate. The moist paste was .Thesecatalysts were tested under identical conditions in the reforming ofnaphtha to convert it to a gasoline product of high'anti-knocl':

value.. The results of these testsare set forth below in Table VI inwhich the data are arranged to show the effect of the catalystcomposition on the activity as reflected by the octane number of thegasoline product.

heated at 1200 F. for one hour and when cooled was made into inchpellets. The catalyst contained 6 weight per cent M003 and 94 weight percent A1203.

Catalyst No. 345.586 grams of activated alumina, containing 8.9 per centwater. and sufficiently finely divided to pass an 80-meshscreen werethoroughly mixed with 6.7 grams of hydrated silicic acid containing 55.2Weight per cent of water. The resulting mixture was then made into apaste with 400 c. c. of solution containing 44.2 grams of ammoniummolybdate. The paste was heated at 1200 F. for one hour and was thenmade into inch pellets. The completed catalyst had the followingcomposition by weight: Al2O3-89 percent, MoOa-fi per cent, and 8102-5per cent.

Catalyst No. 348.-171 grams of titania acid cake containing 87.8 weightper cent solids was washed six times by filtering with 650 c. c. ofwater in each wash. At the conclusion of the sixth wash the filtrate wasstill definitely acid. The washed cake was then dried at 110 C. to awater content of 4 weight per cent. 31.3 grams of the material thusobtained were thoroughly mixed with 553 grams of activated aluminasuffieiently finely divided to pass an 80-mesh screen and containing.8.9 per cent water, and 67 grams of hydrated silicic acid containing55.2 weight per cent water. The resulting mixture was made into a pastewith 400 c. c. of solution containing 44.2 grams of ammonium molybdate.The paste was heated at 1200 F. for one hour and was then made into 1%inch pellets. The catalyst had the following composition by weight:Al2Oa-84 per cent, Mo03-6 per cent, Si02-5 per cent, and TiO25 per cent.

Catalyst No. 378.31.2 grams of the water washed titania acid cakeemployed in catalyst No. 348 were carefully mixed with 527 grams ofactivated alumina containing 8.9 per cent water and sufiiciently finelydivided to pass an 80-mesh screen, 133.8 grams of hydrated silicic acidcontaining 55.2 weight per cent water, and 30 grams of ferric oxide.This mixture was made into a paste with 450 c. c. of solution containing4'7 grams of ammonium molybdate. The moist paste was heated at 1200 F.for one hour, and after cooling the dried material was made into inchpellets. This catalyst had the following composition by weight:A120375.2 per cent, M0Oa-6.0 per cent, Si0a9.4- per cent, Hog-4.7 percent, and F62034.7 per cent.

TABLE VI Catalyst Composition, Wt. Per cent Catalyst Octane NumberNumber M005 S10 'IiOi FezO; A;

Referring in Table VI to catalysts Nos. 270

and 345, it is seen that the incorporation of 5 per cent silica produceda more active catalyst,-

as shown by the increased octane number obtained with catalyst No. 345.Referring to catalyst No. 348, it is seen that the addition of titaniato the composition represented by catalyst No. 345 produced a stillfurther increase in the octane number of the gasoline. Maximum activityin this series was obtained with catalyst No. 378 which containedsubstantial proportions of tita-' nia and iron oxide in addition to thesilica, molybdenum oxide and alumina.

Catalysts Nos. 348, 378, 538, and 583 illustrate the beneficial effectof small proportions of titania or iron oxide or both. In none of thesecatalysts did the amount of these oxides added, alone or in combination,exceed about 10 per cent.

In the foregoing specific examples of the application of the process, tothe treatment of naphtha to produce gasoline of higher anti-knock value,uniform operating conditions are employed to permit a comparison of theresults obtained. In the application of the invention to the treatmentof naphtha the reaction conditions necessarily must be selected withreference to the character of the hydrocarbons being treated, theresults desired and the composition of the catalyst. Treatment ofnaphtha for this purpose should be carried out at temperatures of 850 F.to 1050 F. Within this temperature range space velocities of 0.1 to 3.0volumes of liquid per volume of catalyst space per hour may be employedadvantageously. Hydrogen is circulated through the reaction zone as inthe foregoing specific examples, and this operation may be carriedout'on a recycling basis since hydrogen is produced in the process.Hydrogen is recycled in the amount of 0.5 to 9.0, preferably 3.0,molecules of hydrogen per molecule of hydrocarbon reactants. The

hydrogen may be in admixture with light gaseous hydrocarbons. Therecycling of hydrogen in this Vimile the invention has been described byref-- erence to specific examples involving the treatment of a specificmixtureof hydrocarbons, the invention is also applicable to thetreatment of other mixtures of hydrocarbons or individualhydrocarbons.For example, the invention includes the treatment of individualaliphatic hydrocarbons such as normal heptane to effect conversion toheptene and toluene. Normally gaseous hydrocarbons also are treated inaccordance with the improved process. For example, butane is treated toeflect dehydrogenation thereof to butene, or butene is dehydrogenated tobutadiene. In addition to the production of simple aromatichydrocarbons, as by'treatment of naphthenic or aliphatic hydrocarbonssuch as heptane, the process is applicable to the production of morehighly cyclicized hydrocarbons such as naphthalene and anthracene.-

While the foregoing specific examples of the improved conversion processinvolved the use of a fixed bed of granular catalyst, through which thereaction mixture and the regenerating gases were passed alternately, itis evident that the invention is not limited to operations employing theimproved catalyst in a static condition. The improved process involvesas well the use of the catalyst in granular or powdered form in a movingbody. In this method of operation the cat- .alyst mass moves downwardly,either continuously or intermittently, through the reactor as the resultof continuous or periodic removal of a portion of the catalyst mass atthe bottom of the reactor and corresponding replenishment with fresh orregenerated catalyst at the top of the reactor. In another applicationof the inventionthe powdered catalyst is suspended in the stream 01'reactants and thus passed through the reaction zone with the retactants.In another method of operation the powdered catalyst is maintained as afluidized, or pseudo-fluid, mass in the reaction zone by the passage ofthe vaporized reactants upwardly therethrough. Continuous addition andwithdrawal of catalyst is efi'ected by suspension of catalyst in theflowing stream of reactants and by direct addition and withdrawal bymeans independent of the stream of reactants. In all the operationsinvolving the use of the catalyst in a non-static conditionsubstantially continuous operation is attained in a single reactor, thewithdrawn catalyst being regenerated, or otherwise treated, outside thereactor and returned for further use in the reactor without interruptingthe fiow of reactants therethrough.

This application is a division of prior application Serial No. 447,587,filed June 18, 1942.

I claim:

- 1. A catalyst composition consisting essentially of about 1 to 12percent ofmolybdenum oxide in combination with a carrier essentiallyconsisting of alumina and silica gel in proportions such that the silicaconstitutes about 1 to percent of the catalyst composition.

2. A catalyst composition consisting essentially 01 about 1 to 12percent of an oxide of a metal of the left hand columns of groups V andVI of the periodic table in combination with a carrier essentiallyconsisting of alumina and silica gel in proportions such'that the silicaconstitutes about 1 to 15 percent of. the catalyst composition andcontaining a minor proportion of titania comprising not more than about10 per cent of the catalyst composition.

3. A catalyst composition consisting essentially of about 1 to 12percent of an oxide of a metal of about 1 to 12 percent of an oxide of ametal of v the left hand columns of groups V and VI of the periodictable in combination with a carrier essentially consisting of aluminaand silica gel in proportions such that the silica constitutes about 1to 15 percent of the catalyst composition and containing minorproportions of titania and iron oxide, the titania and iron oxidecomprising not more than about 10 per cent of the catalyst composition.

5. A catalyst composition consisting essentially of about 1 to 12percent of molybdenum oxide in combination with a carrier essentiallyconsisting of alumina and silica gel in proportions such that the silicaconstitutes about 1 to 15 percent of the catalyst composition andcontaining a minor proportion of titania comprising not more than about10 per cent ofthe catalyst composition.

6.,A catalyst composition consisting essentially of about 1 to 12percent of molybdenum oxide in combination with a carrier essentiallyconsisting of alumina and silica gel in proportions such that the silicaconstitutes about 1 to 15 percent of the catalyst composition andcontaining a minor proportion of iron oxide comprising not more thanabout 10 per cent oi the catalyst composition.

7. A catalyst composition consisting essentially 01 about 1 to 12percent of molybdenum oxide in combination with a carrier essentiallyconsisting of, alumina and silica gel in proportions such that thesilica constitutes about 1 to 15 percent of the catalyst composition andcontaining minor proportions of titania and iron oxide, the titania andiron oxide comprising not more than about 10 per cent of the catalystcomposition.

8. A catalyst composition comprising about 1 to 12 per cent ormolybdenum oxide and about 1 to 10 per cent of silica gel, the remainderconsisting essentially of alumina as the major component of saidcatalyst composition.

EDWIN T. LAYNG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

